When filling the fuel tank of a motor vehicle, it is a common measure to recover the vapor escaping the tank when filling it with liquid fuel. This measure is taken for both safety and environmental reasons. The vapor recovery is achieved, for instance, by arranging a vapor suction nozzle next to the fuel dispensing nozzle of a pistol grip for filling the tank with fuel. Vapor is then removed from the tank during filling, at a certain rate, which is often controlled by the standard rate at which fuel is dispensed to the tank. Vapor recovery systems typically comprise a pump for feeding vapor, from the tank of the vehicle, to the fuel container from which fuel is fed to the vehicle. This mutual exchange of vapor/fuel is continuously performed when filling a vehicle with fuel.